Image Gallery: How Ice Drives Death Valley's Sailing Stones

Natural mystery

In Death Valley's Racetrack Playa, rocks seem to slide across the flat lakebed under their own power. Now, scientists have solved the mystery.

Geologic puzzle

rov-rocktrail-100820-02 — (Image credit: NASA/GSFC/Cynthia Cheung.)

The trails are the only evidence the rocks move. Some stretch twice the length of a football field

On the playa

Racetrack Playa rock trails — (Image credit: Richard Norris)

Biologist Richard Norris stands next to a Racetrack Playa rock trail that may have formed in the late 1990s.

The testing ground

Racetrack Playa moving rock — (Image credit: Richard Norris)

A boulder brought in to Racetrack Playa to study its sailing stones. Engineer Jim Norris of Interwoof built the custom GPS unit.

Look closely

The rock on the left side of the photograph is about to move, bulldozed by ice.

There, it moved!

In this photograph, the small white rock has shifted from the left to the right.

Racing rocks

Researchers saw rocks sail across Racetrack Playa and set fresh trails, shown here.

On thin ice

Racetrack Playa ice — (Image credit: Richard Norris)

An thin shard of ice from Racetrack Playa's pond, collected Dec. 20, 2013.

Frozen wonder

A GPS-mounted boulder leaves a trail on Racetrack Playa

New tracks

Parallel trails carved in the wet playa mud.

Becky Oskin covers Earth science, climate change and space, as well as general science topics. Becky was a science reporter at Live Science and The Pasadena Star-News; she has freelanced for New Scientist and the American Institute of Physics. She earned a master's degree in geology from Caltech, a bachelor's degree from Washington State University, and a graduate certificate in science writing from the University of California, Santa Cruz.